The present invention relates in general to liquid distributors and in particular to a new and useful progressive distributor device for a liquid medium which includes a housing for receiving a plurality of movable pistons which operate in a working cycle to discharge liquid.
Progressive or piston distributors of this kind are employed in various industries. If lubricant distribution is needed, the distributor's purpose is to feed the lubricant to a point of lubrication, such as an engaged tooth of a transmission, at a given time and in the necessary amount. The substance is supplied to the progressive distributor under pressure, and this pressure is at the same time used for displacing floating pistons in the distributor. While displacing such a piston from one of its end postions into the other, the lubricant or other substances present in the respective cylinder space is expelled by the leading end of the piston. The amount displaced per working stroke of the piston into the conduit leading to a point of use thus demands on the stroke length and the piston diameter. The pistons act both as working pistons and as control pistons. As a rule, the substance displaced under pressure by the first piston is conducted to flow to, and displace, a second piston. The second piston controls the motion of the third piston in the same way, and so on. As soon as the last piston, after the others, has performed its motion, for example, downwardly, it reverses the control to the effect of now moving the first piston upwardly, for example, and thus to displace the lubricant present at the other end of the piston. Such progressive or piston distributors thus act substantially as metering pumps. With a proper arrangement of the control passages of the piston and the housing, the working cycles uphold themselves automatically as long as lubricant under pressure is supplied. It follows from the foregoing that, for example, two points of use may be supplied with the liquid substance, namely one during the upward motion of the piston and the other during the downward motion thereof. If three pistons are provided, six points of use may be supplied, for example, except that two or more discharge lines at one end of the pistons would be united or branched. It therefore depends on the specific application how may pistons are provided in such a distributor.
Since the various end spaces and annular spaces in the cylinders must be hydraulically connected to each other, as already mentioned, in a way which insures that with a continuing supply pressure the working cycle will continue and automatically recur, the hydraulic connections, mostly designed as internal passages, of a progressive distributor become more complicated, the more pistons the distributor has. The result is that in practice, any number of pistons cannot be provided. Typically, such a progressive distributor will comprise four to six pistons, for example. This also necessarily determines or limits the number of discharge bores of such a progressive distributor.
There are applications, particularly in the lubricating technique, requiring a supply of the liquid substance or lubricant to a great number of locations. This problem can no longer be solved by branching the discharge line, particularly if only a definite amount per working stroke is available and a plurality of points of lubrication are to be supplied simultaneously with this, or even a larger amount. Such problems can be solved only by providing a plurality of progressive distributors. Each of them must be connected to a supply line and separately mounted. In addition, the various discharge lines must be laid. This is considerably expensive, already in the manufacture of the distributors, and because of the space needed.